I just tried to install GraphicsMagick (well, it was pulled in as a dependency), but I get a conflict note with my existing ImageMagick. It tells me I can't have both installed at the same time. I did a web search, and those sites that discuss the compatibility say that both can reside on the same system with no problems. However, most of the web pages that make this claim are several years old.

The current GraphicsMagick page says, "GM does not does not conflict with other installed software." That's pretty vague, but it supports the notion that they should be able to coexist.

So does anyone know why the GraphicsMagick ebuild excludes ImageMagick?

I'm a bit afraid to remove ImageMagick, since I foresee lots of breakage on all kinds of packages that expect IM to be there._________________Ignorance killed the cat. Curiosity was framed.

No, thats braindead. Because graphicsmagick should be a dropin replacement for imagemagick, the USE flag compiles further tools which would conflict with imagemagick since they replace imagemagick.
But gentoo in it's allmighty wisdom choose to make fun of us and forces imagemagick EVEN if there is graphicsmagick with imagemagick USE flag, as GM is superior I feel fooled.

No, thats braindead. Because graphicsmagick should be a dropin replacement for imagemagick, the USE flag compiles further tools which would conflict with imagemagick since they replace imagemagick.
But gentoo in it's allmighty wisdom choose to make fun of us and forces imagemagick EVEN if there is graphicsmagick with imagemagick USE flag, as GM is superior I feel fooled.

PS: so, this is clearly a bug!

Some packages really force imagemagick or graphicsmagick in purpose because neither one is a replacement to anothers libraries. Only 1/3 of the reverse dependencies use the tools, rest use the libraries which don't match at all.

Only 1/3 of the reverse dependencies use the tools, rest use the libraries which don't match at all.

Wouldn't it be time to introduce virtual/imagemagick-tools, finally? This way packages could specify whether they depend on the tools and/or the library instead of playing the confusing and lengthy || ( ... ) game. Moreover, in this way one could easily also introduce media-gfx/imagemagick[tools] (and maybe rename the confusing media-gfx/graphicsmagick[imagamagick] into media-gfx/graphicsmagick[tools]) to allow the user to decide whether he wants the tools from imagemagick or graphicsmagick (as I understood, some users might prefer the latter which is currently impossible). Last but not least, users who need only the libraries (because some program depends on it) are not forced to install the tools at all.

Is there a way to search for any package that requires a dependency with a specific USE flag? I emerged an ebuild a couple weeks ago that explicitly required graphicsmagick with USE="imagemagick" set, which conflicts with a lot of other packages. But now, when I'm running 'emerge -uD world', I'm being told that imagemagick is blocking graphicsmagick, likely for this reason. I'd like to be able to find out which package that was so I can file a bug or something, because having to set/unset that USE back and forth seems somewhat … inefficient.